Bristol boss Pat Lam expects injured England squad scrum-half Harry Randall to be sidelined for seven or eight weeks.
Uncapped Randall was part of England's 28-man Guinness Six Nations squad that prepared for games against Scotland, Italy and Wales last month.
But he then suffered an ankle injury and looks unlikely to be back in action for his club before the start of May.
"Unfortunately, Harry is going to be out for probably another seven, eight weeks, which is obviously frustrating," Bristol rugby director Lam said.
"At the moment, it's eight weeks. The surgeon is comfortable that it doesn't need surgery, otherwise it would have been 12 weeks.
"We saw him and a couple of others down there in the gym this morning, so he is trekking away on that road to recovery."
England head coach Eddie Jones limited his Six Nations squad selection to 28 players in an effort to enhance coronavirus safety measures.
The Rugby Football Union struck an agreement with Premiership Rugby and the Rugby Players' Association that enables the 28 members to remain in camp for the entirety of a Test week.
It was previously customary for Jones to pick an initial training squad of around 32 players that would arrive in camp on a Monday.
This would then be trimmed to a smaller group of 23 to 25 on a Tuesday or Wednesday night, enabling those not in contention to play for England that weekend to turn out for their clubs instead.
Bristol also had full-back Max Malins, prop Kyle Sinckler and back-row forward Ben Earl selected by Jones, although game-time has proved limited for Malins and Earl, while Randall did not feature in any Six Nations matchday 23.
Lam added: "Harry has played no rugby since January 9, and by the time he gets back it's going to be three months of no rugby at all. That's going to be our challenge.
"Max Malins has played 27 minutes in 10 weeks, and Ben Earls has played 45 minutes of rugby in eight weeks, and by the time they get back it is going to be 12 weeks.
"Hopefully, they are going to get some game-time, but if not, that will be our biggest challenge when they get back.
"By the time they get back, we are going into the home stretch with big games in Europe and the Premiership.
"People are going to expect them to be at their best, but that is always going to be difficult when they haven't had much game-time.
"We will deal with it, and we have got to get the work done to try and deal with that challenge.
"The main decision that was made at the beginning (of the Six Nations) was that 28 players were going to be protected and stay (with England). The concern was Covid.
"I think the priority was they wanted to keep their bubble safe. I understand the reasons behind it. The priority was safety."
